Identification and distribution of the clinical isolates of imipenem-resistant Pseudomonas aeruginosa carrying metallo-β-lactamase and/or class 1 integron genes

Abstract

To investigate the distribution of the genes of two major metallo-β-lactamases (MBL; i.e., IMP and VIM) and class 1 integrons (intI) in the clinical imipenem-resistant Pseudomonas aeruginosa, a total of 65 isolates, from a university hospital in Sichuan between December 2004 and April 2005 were screened for MBL genes by PCR using primers specific for bla_IMP-1, bla_VIM and bla_VIM-2 genes. The MBL-positive isolates were further assessed for class 1 integrons by PCR using specific primers. The nucleotide sequences of several PCR products were also determined. The results revealed that the bla_VIM gene was found in 81.5% (53/65) of all isolates, bla_VIM-2 gene was found in only 1 isolate and the intI gene was observed in 45.3% (24/53) of bla_VIM-positive isolates. One isolate carried simultaneously both bla_IMP-1 and intI genes, and to the best of our knowledge this is the first report of such isolate in southwest China. These observations highlight that the genes for VIM β-lactamase and class 1 integrons were predominantly present among the imipenem-resistant P. aeruginosa tested, confirming the current widespread threat of imipenem-resistant, integron-borne P. aeruginosa.

References

[1] ShiriN. V., RonenB. A., YehudaC.. Update on Pseudomonas aeruginosa and Acinetobacter baumannii infections in the healthcare setting. Curr Opin Infect Dis, 2005, 18(4): 306-313

[2] LivermoreD. M., WoodfordN.. Carbapenemases: a problem in waiting?. Curr Opin Microbiol, 2000, 3(5): 489-495

[3] QueenanA. M., BushK.. Carbapenemases: the versatile β-lactamases. Clin Microbiol Rev, 2007, 20(3): 440-458

[4] BoucherY., LabbateM., KoenigJ. E., et al.. Integrons: mobilizable platforms that promote genetic diversity in bacteria. Trend Microbiol, 2007, 15(7): 301-309

[5] YangQ., WeiQ. Z., YuY. S., et al.. Study on the VIM-2 metallo-beta-lactamase-producing Pseudomonas aeruginosa strains in intensive care unit. Chin J Lab Med (Chinese), 2004, 27(10): 678-682

[6] ZhaoZ. W., ZhongW. N., MaW.. Clinical analysis on an outbreak of ventilator-associated pneumonia caused by metallo-β-lactamase-producing Pseudomonas aeruginosa in respiratory intensive care unit. Chin J Resp Critical Care Med (Chinese), 2006, 5(3): 168-171

[7] YangW. Q., ShiL., YinX. L., et al.. Distribution and identification of class 1 integrons and integrated gene cassettes in clinical Pseudomonas aeruginosa in different geographic regions. Chin J Antibiot (Chinese), 2006, 31(1): 15-18

[8] SendaK., ArakawaY., IchiyamaS., et al.. PCR detection of metallo-β-lactamase gene (bla_IMP) in gram-negative rods resistant to broad-spectrum β-lactams. J Clin Microbiol, 1996, 34(12): 2909-2913

[9] WatanabeM., IyobeS., InoueM., et al.. Transferable imipenem resistance in Pseudomonas aeruginosa. Antimicrob. Agents Chemother, 1991, 35(1): 147-151

[10] CornaqliaG., MazzariolA., LaurettiL., et al.. Hospital outbreak of carbapenem-resistant Pseudomonas aeruginosa producing VIM-1, a novel transferable metallo-β-lactamase. Clin Infect Dis, 2000, 31(5): 1119-1125

[11] ZhangY. B., Songs. D., QiW., et al.. Detection of metallo-β-lactamase genes (Imp-1, Vim-1 and Vim-2) by PCR in clinical isolates of imipenem-resistant Pseudomonas Aeruginosa. Tianjing Med J, 2003, 30(3): 131-133

[12] ChenR., PengX. M., ZhuJ. X., et al.. VIM-2 metallo-β-lactamase producing Pseudomonas aeruginosa in brun wards. Clin J Nosocomiol, 2006, 16(7): 734-737

[13] XuY. H., ShenJ. L., YangB. X., et al.. Detection of metallo-beta-lactamase as well as loss of out membrane protein from Pseudomonas aeruginosa. Clin J Nosocomiol, 2005, 15(10): 1085-1089

[14] LiX. Z.. Quinolone resistance in bacteria: emphasis on plasmid-mediated mechanisms. Int J Antimicrob Agents, 2005, 25(6): 453-463

[15] LiX. Z., NikaidoH.. Efflux-mediated drug resistance in bacteria. Drugs, 2004, 64(2): 159-204

[16] ManiatiM., IkonomidisA., MantzanaP., et al.. A highly carbapenem-resistant Pseudomonas aeruginosa isolate with a novel bla_VIM-4/bla_PIb integron overexpresses two efflux pumps and lacks OprD. J Antimicrob Chemother, 2007, 60(1): 132-135

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